zdtm: test_init creates a pid file

Before this patch we use pidof to get a pid of a test process.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -92,6 +92,7 @@ start_test()
 {
 	local tdir=$1
 	local tname=$2
+	local tpid=$tdir/$tname.init.pid
 
 	killall -9 $tname &> /dev/null
 	make -C $tdir cleanout
@@ -100,14 +101,13 @@ start_test()
 		make -C $tdir $tname.pid
 		PID=`cat $test.pid` || return 1
 	else
-		killall -9 test_init
-		$TINIT  $tdir $tname || {
+		$TINIT  $tdir $tname $tpid || {
 			echo ERROR: fail to start $tdir/$tname
 			return 1;
 		}
 
-		PID=`ps h -C test_init -o pid`
-		PID=$((PID))
+		PID=`cat $tpid`
+		ps -p $PID || return 1
 	fi
 }
 

test/zdtm/lib/test_init.c

@@ -19,6 +19,7 @@
 static int sig_received;
 static char dir[PATH_MAX];
 static char name[PATH_MAX];
+static char pidfile[PATH_MAX];
 int status_pipe[2];
 
 static void sig_hand(int signo)
@@ -96,13 +97,14 @@ int main(int argc, char *argv[])
 {
 	void *stack;
 	pid_t pid;
-	int ret, status;
+	int ret, status, fd;
 
-	if (argc < 3)
+	if (argc < 4)
 		exit(1);
 
 	strcpy(dir, argv[1]);
 	strcpy(name, argv[2]);
+	strcpy(pidfile, argv[3]);
 
 	stack = mmap(NULL, STACK_SIZE, PROT_WRITE | PROT_READ,
 			MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS, -1, 0);
@@ -124,5 +126,18 @@ int main(int argc, char *argv[])
 	ret = read(status_pipe[0], &status, sizeof(status));
 	if (ret != sizeof(status) || status)
 		exit(1);
+
+	fd = open(pidfile, O_CREAT | O_EXCL | O_WRONLY, 0666);
+	if (fd == -1) {
+		fprintf(stderr, "Can't create a pid file %s: %m", pidfile);
+		return 1;
+	}
+	ret = dprintf(fd, "%d", pid);
+	if (ret == -1) {
+		fprintf(stderr, "Can't write in a pid file\n");
+		return 1;
+	}
+	close(fd);
+
 	return 0;
 }